[aeronca65tl]

I wrote here previously about my occasional desire to carry a spare tire in my 718 Cayman.

I posted a question about what tire/wheels combo would work, but got no response.

So, I believe I have figured it out. At least for my 2018 base Cayman.

Let me just say that I have no intention of carrying the spare tire when I am driving local here in NJ. The Porsche Road Service combined with the fact that we already have AAA makes carrying a spare unnecessary.
And where I live I never worry about getting a cell signal.

But we have some plans for some longer tours in the Cayman. And if we get a flat tire somewhere near Dingleberry, Utah, I’d like to have some options other than prayer.

I suspected that a 996 or early Boxter spare tire/wheel might work, but was unsure.

Suncoast sells an appropriate spare…...for $1200.

So I called up my fellow MG-racer, Mark who had purchased a very nice 1999 996 about 6 month ago.

He paid $16K for the car. It has 100K miles and is in great shape with all service records. So far, he’s loving it. And, important to me, it has a spare tire.

I drove to Mark’s place with my aluminum race jack, wheel chocks, a torque wrench and other items that would allow me to trial-fit the spare from his 996 onto my Cayman.

I can now say with confidence that the spare tire from his 996 will fit both the front and rear of my 718. I rolled the car at low speed and all seems well (other than the fact that the red wheel looks incredibly dorky).

I am aware there is an issue with what to do with the “flat” tire. After some experimentation, I have found that the front tire/wheel will fit under the rear hatch, but only if the lid is left open about an inch. It will NOT fit in the frunk. If the rear tire/wheel were stowed under the hatch, it would have to be propped open almost two inches. So, not great, but better than walking. I could hold the rear lid closed with a bungie cord and use some clothing or towels to create a cushion between the tire and rear glass. I would put the "flat" tire in a large garbage bag before putting it in the car.

So according to my research a 996 or 6 cylinder Boxter spare will fit my 718. Most of the spare tire/wheels for sale on eBay Motors list them as fitting either the 996 or older Boxter. These wheels are aluminum and are a bright red color. The tire is carried inflated to 60 psi. The tire itself is stamped “Temporary Only” and size is 105/95-R17. Mine is a Continental brand.
The rim looks about 4 inches wide.

I bought an appropriate spare wheel/tire combo on eBay last week. It was listed as coming from an early Boxter. There are plenty of these spare tire/wheel combos for sale on eBay ranging from $75 to $250. I bought a very nice one with proper, Porsche cover for $200 including shipping.

If I got a flat on the front, I’d simply swap the spare in place. But if I got a flat at the back I’d probably put a front tire on the rear and then put the spare on the front. It’s more work but I think the teeny-tiny spare would be better on the front because it would carry less weight and would maintain better ground clearance.

The spare tire/wheel has an outer diameter of about 25”. The stock 18” front wheels are about 26” in outer diameter. The stock 18” rear wheels have an outer diameter of about 27”.
If the spare is used on the front, the car will be a bit less than 1/2” lower on that side. I have verified this with actual measurements. If used on the back, the spare tire would drop that side a little less than one inch (which is why I’d prefer to play musical chairs with the tires if I got a flat on the back).
I can’t say how this would play out on cars that are lowered.

By the way, I occasionally see people commenting that they have chosen the 19” or 20” wheels because they “fill out” the wheel wells better. This is not really correct. The 19” and 20” wheels have a smaller aspect ratio and are essentially the same outer diameter as the 18” versions. Thus, I believe this spare would work fine on the larger diameter wheels as long as the brake calipers are not a lot bigger. On my car with standard brakes, there is lots of clearance between the “red” wheel and the caliper.

The spare tire will fit in the front well of the frunk. Since I only intend to use the spare when I am traveling I will probably use soft luggage packed in front of it to prevent it from moving around. I will also carry a small Toyota scissors jack that I already have (used ones are easy to find online), wheel chocks and a 19 MM socket/handle along with the spare. I plan on welding on a steel bung to the scissors jack so it will locate better in lift points, but this probably isn’t really necessary.

First photo - spare tire on front of my car.

Second photos - spare tire on rear of my car.

Third photo - spare tire (uncovered) in frunk.

Fourth photo – front hub minus wheel

Fifth photo – “flat” front wheel/tire sticking out of frunk: does NOT fit

Sixth photo - “flat” front wheel/tire (in garbage bag) under hatch which will not fully close (about 1” open)

Seventh photo – ground clearance with standard front wheel (approx 5.625”)

Eight photo - ground clearance with spare tire/wheel (approx 5.375”)

 

[Porsche2018]

Great idea but my friend you have way to much time on your hands.:laugh:

 

[Guaji]

My first big road trip (in the 718) up I-95 is planned for mid-May, but I’ll just have to hope that my tires will be fine. I won’t be venturing far from the highway so if I needed any roadside assistance I should be in cell phone range to call Porsche for assistance or AAA.

 

[greywing]

Well researched and very informative. Thanks aeronca65tl for your effort.

 

[Ian718]

Thank you for that write up. Excellent work!

 

[cvb]

Wonder if the flat original tire would fit in the frunk or trunk wince it will be deflated? Also curious about this for Boxster.

 

[aeronca65tl]

Wonder if the flat original tire would fit in the frunk or trunk wince it will be deflated? Also curious about this for Boxster.

No, I really doubt it.

The tire sidewalls on these cars are very short and stiff (45 aspect ratio or even less).

Even with all the air out, the tire is very stiff and not very compressible.

By the way, if you're by yourself, an alternate idea would be to put the flat tire in a garbage bag and put it on the passenger seat.

 

[darell67]

I wrote here previously about my occasional desire to carry a spare tire in my 718 Cayman.

I posted a question about what tire/wheels combo would work, but got no response.

So, I believe I have figured it out. At least for my 2018 base Cayman.

Let me just say that I have no intention of carrying the spare tire when I am driving local here in NJ. The Porsche Road Service combined with the fact that we already have AAA makes carrying a spare unnecessary.
And where I live I never worry about getting a cell signal.

But we have some plans for some longer tours in the Cayman. And if we get a flat tire somewhere near Dingleberry, Utah, I’d like to have some options other than prayer.

I suspected that a 996 or early Boxter spare tire/wheel might work, but was unsure.

Suncoast sells an appropriate spare…...for $1200.

So I called up my fellow MG-racer, Mark who had purchased a very nice 1999 996 about 6 month ago.

He paid $16K for the car. It has 100K miles and is in great shape with all service records. So far, he’s loving it. And, important to me, it has a spare tire.

I drove to Mark’s place with my aluminum race jack, wheel chocks, a torque wrench and other items that would allow me to trial-fit the spare from his 996 onto my Cayman.

I can now say with confidence that the spare tire from his 996 will fit both the front and rear of my 718. I rolled the car at low speed and all seems well (other than the fact that the red wheel looks incredibly dorky).

I am aware there is an issue with what to do with the “flat” tire. After some experimentation, I have found that the front tire/wheel will fit under the rear hatch, but only if the lid is left open about an inch. It will NOT fit in the frunk. If the rear tire/wheel were stowed under the hatch, it would have to be propped open almost two inches. So, not great, but better than walking. I could hold the rear lid closed with a bungie cord and use some clothing or towels to create a cushion between the tire and rear glass. I would put the "flat" tire in a large garbage bag before putting it in the car.

So according to my research a 996 or 6 cylinder Boxter spare will fit my 718. Most of the spare tire/wheels for sale on eBay Motors list them as fitting either the 996 or older Boxter. These wheels are aluminum and are a bright red color. The tire is carried inflated to 60 psi. The tire itself is stamped “Temporary Only” and size is 105/95-R17. Mine is a Continental brand.
The rim looks about 4 inches wide.

I bought an appropriate spare wheel/tire combo on eBay last week. It was listed as coming from an early Boxter. There are plenty of these spare tire/wheel combos for sale on eBay ranging from $75 to $250. I bought a very nice one with proper, Porsche cover for $200 including shipping.

If I got a flat on the front, I’d simply swap the spare in place. But if I got a flat at the back I’d probably put a front tire on the rear and then put the spare on the front. It’s more work but I think the teeny-tiny spare would be better on the front because it would carry less weight and would maintain better ground clearance.

The spare tire/wheel has an outer diameter of about 25”. The stock 18” front wheels are about 26” in outer diameter. The stock 18” rear wheels have an outer diameter of about 27”.
If the spare is used on the front, the car will be a bit less than 1/2” lower on that side. I have verified this with actual measurements. If used on the back, the spare tire would drop that side a little less than one inch (which is why I’d prefer to play musical chairs with the tires if I got a flat on the back).
I can’t say how this would play out on cars that are lowered.

By the way, I occasionally see people commenting that they have chosen the 19” or 20” wheels because they “fill out” the wheel wells better. This is not really correct. The 19” and 20” wheels have a smaller aspect ratio and are essentially the same outer diameter as the 18” versions. Thus, I believe this spare would work fine on the larger diameter wheels as long as the brake calipers are not a lot bigger. On my car with standard brakes, there is lots of clearance between the “red” wheel and the caliper.

The spare tire will fit in the front well of the frunk. Since I only intend to use the spare when I am traveling I will probably use soft luggage packed in front of it to prevent it from moving around. I will also carry a small Toyota scissors jack that I already have (used ones are easy to find online), wheel chocks and a 19 MM socket/handle along with the spare. I plan on welding on a steel bung to the scissors jack so it will locate better in lift points, but this probably isn’t really necessary.

First photo - spare tire on front of my car.

Second photos - spare tire on rear of my car.

Third photo - spare tire (uncovered) in frunk.

Fourth photo – front hub minus wheel

Fifth photo – “flat” front wheel/tire sticking out of frunk: does NOT fit

Sixth photo - “flat” front wheel/tire (in garbage bag) under hatch which will not fully close (about 1” open)

Seventh photo – ground clearance with standard front wheel (approx 5.625”)

Eight photo - ground clearance with spare tire/wheel (approx 5.375”)

I like the Porsche Emblem behind your side mirror...Is that something you just add on?

 

[aeronca65tl]

I like the Porsche Emblem behind your side mirror...Is that something you just add on?

It's magnetic. My wife found a decent image of the Porsche crest and she used one of the online sticker companies to make a few of them. Not sure which company she did this with.

It's nice because I can remove them for washing or if I get tired of them. I have an extra one stuck on the back door of my Chevy tow van

 

[darell67]

It's magnetic. My wife found a decent image of the Porsche crest and she used one of the online sticker companies to make a few of them. Not sure which company she did this with.

It's nice because I can remove them for washing or if I get tired of them. I have an extra one stuck on the back door of my Chevy tow van

Thank you!

 

[thunderstrike]

I carry an Off Road Tire Repair Kit plus an Heavy Duty 12v Air Pump I use with my Jeep Wrangler when I' 4-wheeling.

 

[ian718cayman]

I wrote here previously about my occasional desire to carry a spare tire in my 718 Cayman.

I posted a question about what tire/wheels combo would work, but got no response.

So, I believe I have figured it out. At least for my 2018 base Cayman.

Let me just say that I have no intention of carrying the spare tire when I am driving local here in NJ. The Porsche Road Service combined with the fact that we already have AAA makes carrying a spare unnecessary.
And where I live I never worry about getting a cell signal.

But we have some plans for some longer tours in the Cayman. And if we get a flat tire somewhere near Dingleberry, Utah, I’d like to have some options other than prayer.

I suspected that a 996 or early Boxter spare tire/wheel might work, but was unsure.

Suncoast sells an appropriate spare…...for $1200.

So I called up my fellow MG-racer, Mark who had purchased a very nice 1999 996 about 6 month ago.

He paid $16K for the car. It has 100K miles and is in great shape with all service records. So far, he’s loving it. And, important to me, it has a spare tire.

I drove to Mark’s place with my aluminum race jack, wheel chocks, a torque wrench and other items that would allow me to trial-fit the spare from his 996 onto my Cayman.

I can now say with confidence that the spare tire from his 996 will fit both the front and rear of my 718. I rolled the car at low speed and all seems well (other than the fact that the red wheel looks incredibly dorky).

I am aware there is an issue with what to do with the “flat” tire. After some experimentation, I have found that the front tire/wheel will fit under the rear hatch, but only if the lid is left open about an inch. It will NOT fit in the frunk. If the rear tire/wheel were stowed under the hatch, it would have to be propped open almost two inches. So, not great, but better than walking. I could hold the rear lid closed with a bungie cord and use some clothing or towels to create a cushion between the tire and rear glass. I would put the "flat" tire in a large garbage bag before putting it in the car.

So according to my research a 996 or 6 cylinder Boxter spare will fit my 718. Most of the spare tire/wheels for sale on eBay Motors list them as fitting either the 996 or older Boxter. These wheels are aluminum and are a bright red color. The tire is carried inflated to 60 psi. The tire itself is stamped “Temporary Only” and size is 105/95-R17. Mine is a Continental brand.
The rim looks about 4 inches wide.

I bought an appropriate spare wheel/tire combo on eBay last week. It was listed as coming from an early Boxter. There are plenty of these spare tire/wheel combos for sale on eBay ranging from $75 to $250. I bought a very nice one with proper, Porsche cover for $200 including shipping.

If I got a flat on the front, I’d simply swap the spare in place. But if I got a flat at the back I’d probably put a front tire on the rear and then put the spare on the front. It’s more work but I think the teeny-tiny spare would be better on the front because it would carry less weight and would maintain better ground clearance.

The spare tire/wheel has an outer diameter of about 25”. The stock 18” front wheels are about 26” in outer diameter. The stock 18” rear wheels have an outer diameter of about 27”.
If the spare is used on the front, the car will be a bit less than 1/2” lower on that side. I have verified this with actual measurements. If used on the back, the spare tire would drop that side a little less than one inch (which is why I’d prefer to play musical chairs with the tires if I got a flat on the back).
I can’t say how this would play out on cars that are lowered.

By the way, I occasionally see people commenting that they have chosen the 19” or 20” wheels because they “fill out” the wheel wells better. This is not really correct. The 19” and 20” wheels have a smaller aspect ratio and are essentially the same outer diameter as the 18” versions. Thus, I believe this spare would work fine on the larger diameter wheels as long as the brake calipers are not a lot bigger. On my car with standard brakes, there is lots of clearance between the “red” wheel and the caliper.

The spare tire will fit in the front well of the frunk. Since I only intend to use the spare when I am traveling I will probably use soft luggage packed in front of it to prevent it from moving around. I will also carry a small Toyota scissors jack that I already have (used ones are easy to find online), wheel chocks and a 19 MM socket/handle along with the spare. I plan on welding on a steel bung to the scissors jack so it will locate better in lift points, but this probably isn’t really necessary.

First photo - spare tire on front of my car.

Second photos - spare tire on rear of my car.

Third photo - spare tire (uncovered) in frunk.

Fourth photo – front hub minus wheel

Fifth photo – “flat” front wheel/tire sticking out of frunk: does NOT fit

Sixth photo - “flat” front wheel/tire (in garbage bag) under hatch which will not fully close (about 1” open)

Seventh photo – ground clearance with standard front wheel (approx 5.625”)

Eight photo - ground clearance with spare tire/wheel (approx 5.375”)

Incredibly informative, thanks! You saved me so much time researching! I’m in NJ too and also planning a long distance road trip.

I think I might try and build something custom to mount the spare externally. Anyone have any thoughts on that?

 

[aeronca65tl]

……..Anyone have any thoughts on that?

There is an official roof rack from Porsche for a 911. I can't imagine what it would cost but maybe it would give some ideas about construction. I took this photo at the 70th NNJR-PCA event at Met-Life Stadium.

 

[ian718cayman]

There is an official roof rack from Porsche for a 911. I can't imagine what it would cost but maybe it would give some ideas about construction. I took this photo at the 70th NNJR-PCA event at Met-Life Stadium.

I almost went to that event, but unfortunately was out of the country.

I don't believe the 718 Cayman has the slots for OEM roof rails, right? I don't have my Cayman yet, awaiting a custom order

I am thinking about purchasing the SeaSucker Monkey Bars and building a wheel mount and attaching it to either the roof or possibly the rear glass.

Ugh, sorry, too new of a user to post a link, but you can google "SeaSucker Monkey Bars" and see what I am talking about.

 

[aeronca65tl]

I saw a 911 with a bike rack that looked like that "SeaSucker Monkey Bars". Looked a little bit sketchy but if you keep checking it and only used it in emergenceies, I'm sure it would work.

And you are correct......my 718 Cayman doesn't have any roof rails like a 911.

By the way, the local PCA here in north-NJ is a nice group. We've done e few events with them in 2019.

https://nnjr-pca.com/

 

[nineball]

I don't believe the 718 Cayman has the slots for OEM roof rails, right? I don't have my Cayman yet, awaiting a custom order

this is correct. pre-718 had the provisions for the roof rack, the 718 does not. i was quite bummed about this as i planned on building my own roof rack to transport my track wheels but upon delivery found out the truth. i was told that porsche is developing a roof rack system for the 718 but i don't have high hopes as it's been almost 2 years and i still haven't seen it. additionally it would have to be some sort of a clamping system due to lack of mounting locations and that doesn't really interest me.

 

[LittleBlueGT]

OD of the front tires on a 718 are about 26.5, rear tire is 27.3!

What is the OD of your spare? I suspect if you had PTV that it could easily overheat the rear LSD, no?

 

[nineball]

OD of the front tires on a 718 are about 26.5, rear tire is 27.3!

just for comparison based on a 20" stock setup

 

[aeronca65tl]

OD of the front tires on a 718 are about 26.5, rear tire is 27.3!

What is the OD of your spare? I suspect if you had PTV that it could easily overheat the rear LSD, no?

The spare is about 25" in diameter. I don't have a limited slip diff so this does not affect me.

But regarding the technical question of overheating with different size tires on the rear: Porsche sold the 996 with an available limited slip diff and those cars also had this same style temporary donut spare.

That's not a definitive answer to your question but it leads me to believe that it might be OK.

 

[LittleBlueGT]

Porsche sold the 996 with an available limited slip diff and those cars also had this same style temporary donut spare.

And the 996 had a different wheel tire combo. I can guarantee that the OD of the spare was the same size as the OEM tires.


How much of an OD difference will overheat things or cause damage, IDK, but back in the Subaru world I was always under the impression that less then 3% would probably work. It depends in speed driven, distance driven, etc....

But I absolutely would not run a 6% difference in OD tires on a car with PTV.